MINERAL-COMPOSITION OF ISOLATED FIBER FRACTIONS FROM ARTICHOKE AND THE EFFECT OF PHOSPHATE BUFFER ON ITS STRUCTURE AND MINERAL-CONTENT

Soluble and insoluble dietary fibre of artichoke heart were extracted in water and phosphate buffer to determine their mineral contents and to evaluate the effect of the extraction medium on fibre structure (st udied by scanning electron microscopy) and mineral composition (determ ined by X-ray microanalysis and atomic absorption spectrophotometry). The undialysed soluble dietary fibre extracted with phosphate buffer s howed a different structural organisation from that extracted with wat er. X-Ray microanalysis of both soluble fractions showed some differen ces between the Na, K, Ca and P contents, and also between the Na cont ents of the insoluble fractions. However, when the samples were dialys ed, differences in morphology and structure between the soluble fracti ons were not observed. A study of the mineral composition by atomic ab sorption showed differences between both soluble fractions and both in soluble fractions as regards Na, Ca, Mg and Fe. (C) 1997 Elsevier Scie nce Ltd.